Fix spi_flash_write_page to stop at len or page boundary

[danielinux]

• Added unit tests for spi_flash.c

Ref: Fenrir / M-1

[Copilot]

Pull request overview

This PR fixes a bug in spi_flash_write_page where the write loop could continue past the requested data length when crossing page boundaries, and adds comprehensive unit tests to verify the fix.

Changes:

• Fixed the page write loop termination condition to respect both length and page boundary constraints
• Added new unit test file with 8 test cases covering write, read, erase, and error scenarios
• Updated build configuration to include the new unit test target

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated no comments.

File	Description
src/spi_flash.c	Fixed do-while loop to check both len and page boundary before continuing
tools/unit-tests/unit-spi-flash.c	Added comprehensive unit tests with SPI mock for testing flash operations
tools/unit-tests/Makefile	Added unit-spi-flash to test targets list
.gitignore	Organized unit test binary entries with proper section header

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